The present invention relates to surgical apparatus and procedures, and particularly to a device for excising portions of the atherosclerotic plaque material causing stenosis in an artery.
Atherosclerosis is a condition which progressively affects many arteries of the body with advancing age. It ultimately produces thickening of the medial layer of the arterial wall, which may involve some or all of the circumference of the blood vessel. Eventually, significantly narrowed internal diameter, or stenosis, of the artery results and restricts the flow of blood to the tissue beyond the stenosis, producing symptoms including angina or myocardial infarction in the heart, claudication or gangrene in the legs, high blood pressure, or deterioration of kidney function.
The art and science involved in modern vascular surgery are comparatively young and began with the successful end-to-end repair of severed arteries in Korean war casualties. Atherosclerotic narrowing of arteries then could only be corrected by complete endarterectomy, which required a longitudinal incision through the entire narrowed segment of an artery. Exposure of an artery for this purpose was difficult, and the wounds resulting from the surgery were large. Although results were often gratifying, the practice was not widespread because of resulting problems such as pseudoaneurysms developing in endarterized segments and the potential for vessel wall dissection at the distal endpoint, and because of the difficulty posed both for the patient and for the surgeon. During the 1950's a variety of synthetic tubular grafts were introduced and perfected for partial arterial replacement and bypasses around stenoses. Because of the relative ease of such procedures by comparison with endarterectomy, bypass grafting soon became the dominant means of correcting arterial narrowing within the pelvis and thigh. Advances in surgical technique in the late 1960's made possible the use of the patient's own reversed saphenous vein to bypass occluded arteries on the heart and below the knee.
As the population of the United States has aged as a group, the manifestations of atherosclerosis have, as a group, become this nation's number one health problem in terms of both suffering and cost. While surgical bypass procedures using saphenous vein or prosthetic conduit remain the procedure of choice in most instances, newer technologies have evolved in the last decade to simplify the treatment of atherosclerotic stenoses in an attempt to reduce patient risk, reduce cost, and to make treatment available to more people. In carefully selected cases involving narrowing of short segments of the coronary, renal, iliac, and femoral arteries balloon dilation has been employed with some success. Generally, however, the duration of arterial patency resulting from such procedures is less than for bypass graft procedures. Utilization of lasers to open narrowed arteries has not yet proven to be clinically successful and is very expensive in all aspects.
In recent years a variety of atherectomy devices have been used experimentally in attempts to extend patency. Some of these devices include rotary cutting mechanisms, which restrict their use to stenoses of short length. Some are driven by high-speed electric motors which add to their complexity and increase the likelihood of breakdown while also reducing the amount of responsiveness and taking the ability to control operation out of the surgeon's hands.
Manually-operated devices for relieving arterial stenoses are disclosed, for example, in Lary U.S. Pat. No. 4,273,128, which discloses a device having a plurality of curved knife blades whose edges are directed radially outward, and Fischell et al. U.S. Pat. No. 4,765,332, which discloses a catheter including a proximally-exposed annular cutting edge which is no greater in diameter than an outer sleeve of the catheter to which it is attached. Luther U.S. Pat. No. 4,650,466, discloses a catheter which includes an expansable woven tube portion which can be used to abrade atherosclerotic plaque from the interior wall of the artery. Clark, III, U.S. Pat. No. 4,020,847, discloses a catheter device including a slot having sharp edges extending longitudinally of the catheter to free dangling matter attached inside an artery, which might otherwise obstruct the lumen of the artery.
Hoffman U.S. Pat. Nos. 2,730,101 and 816,552 disclose teat bistoury devices including blades which can be bowed outwardly along the length of each blade to protrude radially. The device is intended to be rotated to cut away restrictions in a milk canal of a cow's teat.
Several prior art devices useful for manually opening venous valves are disclosed in Chin et al. U.S. Pat. Nos. 4,739,760 and 4,768,508 and Reed U.S. Pat. No. 4,655,217. Chin U.S. Pat. No. 4,559,927 discloses an endarterectomy apparatus including a center-pull annular cutter for removing arteriosclerotic material.
Rotary, mechanically operated devices are disclosed in such patents as Sokolik U.S. Pat. No. 3,320,957, which discloses a device including an array of helical stationary blades inside which an oppositelytwisted helical rotor operates to shear material protruding inwardly between the stationary blades. Auth U.S. Pat. No. 4,445,509 discloses a fluted rotary burr. Kensey U.S. Pat. Nos. 4,589,412 and 4,631,052 disclose turbine-driven rotary devices for opening obstructed arteries, and Kensey et al. U.S. Pat. No. 4,681,106 discloses another turbine-driven rotary cutting device.
Several devices for use in retrieving stones from within bodily passageways by entrapping the stones within baskets including arrays of helical wires are disclosed in Grayhack et al. U.S. Pat. No. 4,611,594, Duthoy U.S. Pat. No. 4,625,726, Dormia U.S. Pat. Nos. 4,347,846 and 4,612,931. Related devices are disclosed by McGirr U.S. Pat. No. 4,807,626, and Hawkins, Jr. et al. U.S. Pat. No. 4,790,812, which discloses a parachute-like basket carried on a distal end of a rotatable interior member of a catheter so that the parachute-like basket can retrieve particles cut free by the interior member of the catheter. Park U.S. Pat. No. 3,704,711 discloses a device in which a radially outwardly disposed edge can be controllably concealed within a distal end of a catheter or exposed so that the blade can be used.
Balloon-tipped catheters are disclosed in Fogarty U.S. Pat. No. 3,435,826, while Fogarty U.S. Pat. No. 3,472,230 discloses a catheter including an umbrella-like skirt useful for retrieval of stones.
There still remains a need, however, for an improved atherectomy device which is simple in concept and operation, manually operable, and immediately responsive, and which is useful for all stenoses regardless of the length of the area of stenosis. There is also a particular need for such a device which can be made small enough for surgical removal of plaque from smaller arteries such as those of the heart.